One particular example for a conventional drywall construction is a separation wall. The separation wall is formed by a sub-construction to which plasterboards are screwed. The fixed plasterboards form a closed layer which is the basis for the application of coating materials, wall colors, etc. The sub-construction is made by a plurality of drywall profiles, each profile being aligned corresponding to the orientation of the finished wall.
A conventional drywall profile has a cross section comprising a first flange portion and parallel thereto a second flange portion, both flange portions being connected by a base portion so as to form a u-shape. The plurality of drywall profiles are arranged so that the first flange portions allow for fixing a first layer of plasterboards thereto, and the second flange portions allow for fixing a second layer of plasterboards thereto, which means that the flange portions are arranged in a common plane. The size of the base portion defines the distance between both layers of the attached plasterboards.
Such a layer of plasterboards can be a single layer, a double layer or a multiple layer of plasterboards. Additional layers are sometimes preferred to increase the physical properties of the entire construction.
A high-quality example for the plasterboard is the KNAUF gypsum plasterboard with the product name “diamond” which provides an excellent overall quality. However, the meaning of the term “plasterboard” is understood to be very broad so as to include gypsum plasterboards of specific characteristics, like fire resistance, etc. The term “plasterboard” is defined herewith so as to include plate shaped building panels which can be applied to a drywall sub-construction.
Acoustics in a room can be influenced by the installation of specific drywall constructions, like acoustic walls or acoustic ceilings. Acoustic walls do acoustically separate two rooms so that noise generated in one room is attenuated by the wall so as to be less perceivable in the other room. The use of such acoustic walls provides strong attenuation compared to other wall types.
Room acoustics deal with sound behavior in an enclosed space. The soundwave propagates in the enclosed space of the room and is reflected at the walls, floor and ceiling. The acoustics of a room can be changed by attenuating the sound wave. Attenuation of sound waves can be achieved in many ways, inter alia by damping, diffusion, reflection or absorption.
For example in the widely used drywall construction of an acoustic ceiling, the sound is attenuated by reflection. The sound wave propagating in the room enters the space behind the plasterboard via perforations formed in the plasterboard. In the space behind the plasterboard sound waves propagate and are reflected at the surfaces (e.g. raw ceiling) and peters out in the space between the plasterboard and the raw ceiling.
It is generally possible to achieve sound attenuation by way of acoustic resonance sound absorption, either. A resonant absorber damps the sound wave by reflection thereof. One example for a resonant absorber is a plate resonator which is described in the prior art document DE1950651 1. The plate resonator is used for damping sound of low frequencies in a room, like a concert hall. The plate resonator basically consists of a thin front plate with low internal friction and a thick back plate with high internal friction which are firmly connected to each other.
The plate resonator has the disadvantage that it needs much space to be mounted at the surface of the wall. A further disadvantage is the visual appearance since the plate resonator covers a huge portion of the wall and makes a very technical optical impression.
Another example for a resonant absorber is a Helmholtz resonator. This technique is known from ancient times when clay jugs where arranged in churches to provide a resonant volume for improving the acoustics. The Helmholtz resonator couples sound waves into the volume of a resonance chamber via an opening in the chamber. The sound absorption is achieved for frequencies close to the resonance frequency of the Helmholtz resonator which is related to the size and shape of the volume of the chamber and of the size and shape of the opening through which sound enters the resonator chamber. The damping effect occurs for frequencies which are a multiple of the resonance frequency (1., 2., 3., . . . order harmonics) as well. Wherein damping intensity decreases for an increasing higher order of the resonance frequency.
Therefore, a need exists to address the problems with the prior art with regard to resonance sound absorption.